1. Field of the Invention
The present invention relates to a structured document management system and a structured document management method which manage a large-scale structured document while enabling editing it, and to a search device and a search method which search an ancestor-descendant relation between elements in a managed structured document.
2. Description of the Related Art
Structured documents such as XML have been stored into a database to be used for searching of the contents or document structures and partial reuse. Generally, in a small document including several pages, one person often creates and edits the document. Even when a structured document is stored into a database, the entire document to be edited is often edited. However, in a large-scale document, plural persons edit the respective parts in charge in the document. Even when a structured document is stored into a database, such a cooperative editing environment must be supplied.
In the case of storing a structured document into a database, the structures in the document have been retained by connecting them by a pointer indicating a parent-child relation between elements in the document, or the structures have been retained using an index table showing the structure. Other several methods are considered, and all the related art methods uniformly retain the entire document in a standardized data format.
When such a related art method for storing a structured document is used and an edited document is stored, the influence will, not infrequently, extend over the entire document. When considering the abovementioned cooperative editing environment, plural persons cannot edit a structured document at the same time in the related art.
When editing affects the entire document, data of the entire document must be restructured each time the document is edited. In a large-scale document, such data restructuring requires enormous processing time, and data restructuring for each editing makes the efficiency very low.
On the other hand, when a structured document is stored into a database in this manner, searching of document structures, particularly searching of an ancestor-descendant relation between two elements is performed frequently. The ancestor-descendant relation shows a relation between elements in which a certain element can be traced to an upper layer element or to a lower layer element. A parent-child relation is the relation in which two elements are directly connected in an upper-lower relation. The ancestor-descendant relation includes the parent-child relation.
Since such searching of an ancestor-descendant relation is performed frequently, it is desirably performed fast. In the related art, it is performed by tracing elements one by one. There are many branches, and in a deep-hierarchy document, the element searching time becomes long. For this reason, there has been desired a method which can efficiently search an ancestor-descendant relation in a large-scale document.